Arrangement for heating drying drums of drying machines



April 7, 1964 H. GERSTER v 3,128,157

ARRANGEMENT FOR HEATING DRYING DRUMS OF DRYING MACHINES Filed Feb. 15,1961 2 Sheets-Sheet l INVENTOR.

HEINRICH GERSTER IQQAiof ATT RNEYS H. GERSTER April 7, 1964 ARRANGEMENTFOR HEATING DRYING DRUMS 0F DRYING MACHINES Filed Feb. 15, v1961 2Sheets-Sheet 2 40 e i e e e e 6 I? HEINRICH GERSTER INVENTOR.

A TTORNE Y5 FIGS United States Patent 3,128,157 ARRANGEMENT FDR HEATINGDRYENG DRUM 8F DRYING MACHENES Heinrich Gerster, Industriestrasse ii,Bruehsal- Karisdorf, Baden, Germany Filed Feb. 15, 1961, Ser. No. 39,458Claims priority, appiication Germany Feb. 19, 19hr) 4 Claims. (Cl.34-48) The present invention relates to an arrangement for heating thedrying drum of a drying machine used for drying photographic printswhich drum is rotatably supported on an essentially horizontal shaft andagainst which abuts over a peripheral section thereof a drying clothmoved in the same direction as the drum which drying cloth is in theform of an endless band or belt.

The drying drums of the known prior art drying machines are heated bythe supply of warm air to the drum inside. By reason of the relativelyslight heating capacity of the air, the sections of the drum serving forpurposes of drying which consist of relatively thin steel sheet metalparts, are cooled off relatively very rapidly and are not brought back,by means of the warm air, sufficiently rapidly to the temperaturerequired for drying. The warm or heated air serving for purposes ofheating also should not exceed a predetermined temperature as with theuse of excessively high temperatures, there exists the danger of unevenheating with the consequence of uneven drying and local overheating ofthe drum. Accordingly, the heating of the drying drum with warm airleads to frequent, unpleasant and annoying occurrences of defectiveoperation as regards the dried prints and therewith involves additionalexpenses.

It has already been attempted in the prior art to achieve a better heatconduction and heat distribution by an internal layer or coating of amaterial offering good heat conducting characteristics, for example, byplating the inner side of the drum with copper or the like. Suchmeasure, however, does not entail the expected advantages and, undercertain circumstances, causes the contrary effect, for example, in caseof a plating which is not completely satisfactory. This is so as inthose places in which the material applied to the base material does notabut thereagainst closely to form good contact therewith,heat-insulating air gaps result therefrom by means of which the heattransfer is additionally deteriorated.

Drum heating devices are also known in the prior art in which theannular space of a double-walled drum is filled with liquid and iselectrically heated. However, the prior art realization of suchconstruction is very complicated and involves very high manufacturingcosts. Additionally, the circulation of the liquid can be attained onlywith great difiiculties and often times is the cause of breakdowns ortroubles in the operation thereof.

The present invention is based on the aim to create an installation inwhich the sections of the drying drum, intended for the drying of thephotographic prints, can be heated, during rotation thereof,sufficiently and evenly without great expenditures. This aim andresulting problems are solved in accordance with the present inventionby a drying drum, constructed in a fluid-tight manner, which is providedon the inside space thereof with spray installations by means of which asection of the drum casing is adapted to be sprayed by means of a liquidheat carrier or heating medium maintained at a predeterminedtemperature. With the use of a heat carrier or heating medium of largeheating capacity, such as, for example, water, a relatively slightamount of the heating carrier is sufiicient for the attainment of theintended purpose and, as a result thereof, the supply lines or conduitsfor the heat carrier may be kept relatively small. Moreover, forexample, only a single spraying installation may be "ice sufficient ifthe heat carrier has sufficient heat capacity and the drum diameter doesnot exceed a predetermined dimension so that a sufficiently largesection of the drying drum is heated thereby.

Appropriately, the heat carrier or heating medium is circulated within acirculatory system which consists of a temperature control vessel orcontainer, arranged externally of the drum, for the heat carrier orheating medium with installations for the selective control of apredetermined temperature and of a circulating pump for drawing in theliquid heat carrier or heating medium from the drying drum and/orforcing the heat carrier into the drying drum.

In one advantageous arrangement of the installation according to thepresent invention, the drum axle is constructed as a stationary hollowshaft with externally arranged roller bearings for the drum, and thepressure line as well as the suction line leading to the lowest point ofthe drum are extended through the hollow shaft and are connectedexternally thereof with the temperature control vessel and thecirculating pump. Appropriately, the pressure line and the suction lineare constructed as flexible pressure hoses adapted to be detachablysecured to pipe connections or nipples at the temperature control vesselor container and the suction pump, and the pressure line is extended tothe spray installation out of the hollow shaft through an apertureprovided therein.

However, it is also understood that the hollow shaft, if constructed soas to be closed on all sides thereof to be fluid-tight, may beconstructed itself also as pressure line from which a stationary pipeleads to the spray installation whereas the suction line is extended, ina fluid-tight manner, through the hollow shaft out of the drum innerspace toward the outside thereof. The use of only a single sprayinstallation may be sufficient if the spray installation, according to afurther feature of the present invention, is arranged below the upperapex or top point of the drum and is so constructed that the heatcarrier or heating medium is adapted to be sprayed, from both sidesthereof, toward the drum casing. The spray installation is therebysecured with the aid of appropriate securing members on the hollowshaft. With a sufficient speed of the sprayed or discharged heatcarrier, the latter runs off along the inner walls of the drum casingand forms in the lower part of the drum a heat carrier sump.

In case a single spray installation is not sufiicient, additional sprayinstallations, for example, with relatively larger drums, may bearranged, distributed over the section of the drum to be heated.

It is of particular advantage with the drum heating system in accordancewith the present invention that the heat carrier sump which is formed inthe lower portion of the drum area, represents the relatively coolestplace of the system from which the temperature gradually increases alongthe drum walls in the upward direction up to the point of impingement ofthe spray jets. This is so as it has been found advantageous to treatthe photographic prints to be dried initially at relatively lowertemperatures and to increase the temperature gradually. Since the heatcarrier sump is located in proximity to the place of input, i.e., t0 theplace where the prints initially come into contact with the drum,whereas the place of impingement of the heat carrier is located near theoutlet of the prints, i.e., near the place where the prints are removedfrom operative engagement with the drum, there is achieved additionallya favorable temperature distribution over the drum surface by theinstallation according to the present invention.

The temperature distribution over the drum surface can be additionallycontrolled and regulated by the provision of two or more separate heatcarrier circulatory sys tems, each provided with a temperature controlvessel, a

3 circulating pump and a spray pipe whereby the zones of highesttemperature are to be located in the upper drum area.

Accordingly, it is an object of the present invention to provide aheating installation for drying machines, especially drying apparatusfor drying photographic prints which eliminates the inadequacies andshortcomings of the prior art installations.

It is another object of the present invention to provide a heatingsystem for heating the wall surfaces of a drying drum which is simple inconstruction, inexpensive in manufacture as well as in operation andcompletely satisfactory for the intended purposes.

Still a further object of the present invention resides in the provisionof a heating system that permits the utilization of a heat carrier orheating medium of large thermal capacity for effectively heating, in apredetermined manner, a section of a drying drum forming part of adrying machine.

Still another object of the present invention resides in the provisionof heating means for the drum walls of a drying apparatus, especiallyfor drying photographic prints which permits the realization of apredetermined temperature gradient in a simple and eflicient manner.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein FIGURE 1 is a longitudinal crosssectional view through the drying drum provided with parts of theheating installation according to the present invention,

FIGURE 2 is a cross sectional view, on an enlarged scale, of a detailrelating to the seal used in the drying machine according to the preesntinvention,

FIGURE 3 is a somewhat schematic longitudinal cross sectional view, onan enlarged scale, through the drying drum illustrated in FIGURE 1, and

FIGURE 4 is a somewhat schematic side elevational view of the dryingdrum illustrated in FIGURE 3, but additionally showing a further spraymeans with its circulatory connections together with a heat reflector.

Referring now to the drawing wherein like reference numerals are usedthroughout the various views to designate like parts, and moreparticularly to FIGURE 1, reference numeral '1 designates therein aframe of any suitable construction to which is secured, in anon-rotatable manner, a hollow shaft 3. The drying drum essentiallyconsisting of the two end walls 5 and the outer cylinder casing 6 whichis finished to a high polish and surface-protected, is rotatablysupported on the shaft 3 by means of roller bearings 8. A drying cloth10 or the like of any suitable material which is constructed as endlessband abuts against a relatively large portion of the periphery of thedrumcasing 6. The drying cloth 10, constructed as endless band isreturned upon itself by means of rollers 12 supported within the frame 1over the section thereof resting against the drum casing 6, as isclearly shown in FIGURE 4 of the drawing. The drum assembly 5, 6 issupported on shaft '3 in a freely rotatable manner whereas the dryingcloth 10 is driven with the aid of any suitable motor, not illustratedherein so that the drum is effectively taken along in the rotarymovements thereof by the movement of the belt-type cloth 10.

An inwardly open, annular trough or stiffening corrugation is providedalong the outer circumference of each end wall 5 which serves for theaccommodation of a sealing ring 14 made of flexible or yielding materialand having an essentially U-shaped cross section. The cross section ofthe U-shaped sealing ring 14 is provided with a gap 14' intermediate theleg portions thereof as illustrated on a larger scale in FIGURE 2. Thelateral rim portions of the cylinder casing 6 are inserted duringassembly of the drum into the open gap 14' of the annular sealing ring14 so that they do not come in direct contact with the end walls 5. Thedrying drum is kept together in a fluid-tight manner by several tie-rodsor tensioning rods 16 extending through the end walls 5.

A water tank or reservoir 13 (FIGURES 3 and 4) is disposed below thedrying drum 5, 6 within the contours of the frame 1. A line 20,extending through the hollow shaft 3, leads from tank 18 to a spray pipe22 which is provided on two sides thereof with spray nozzles 23 directedupwardly obliquely toward the cylinder casing 6. The spray pipe 22 is soarranged below the top point or apex of the drying drum 5, 6 that theconnecting rods 16 may pass over the spray pipe 22 during rotation ofthe drum. The spray pipe 22 is secured on the hollow shaft 3 with theaid of two securing members 25. The securing members 25 are therebyprovided at the two ends thereof with clamps for the support of thespray pipe 22 and for the securing thereof on the hollow shaft 3.

A suction line 30, passing through the hollow shaft 3, is extendedwithin the drum inner space 5, 6 to the lowest point of the drum 5, 6.The suction line 30 is operatively connected outside of the drum 5, 6with a pump 32 of any suitable construction which is driven in anysuitable manner, for example, from -a motor (not illustrated). Thepressure side of the pump 32 is operatively connected with thetemperature control vessel or container 18. A heating rod 34 orequivalent heating means, operatively connected with the electric powerline is located with the temperature control tank or vessel 18. Thetemperature of the water within the tank or vessel 18 is indicated by athermometer '36 (FIGURE 3) the sensing element 38 of which is arrangedwithin the temperature regulating vessel 18. A thermostat 46*, thesensing element 42 of which is also disposed within the temperaturecontrol vessel 18, controls, in a manner known per se, the supply ofelectric current to the heating rod 34.

Possibly, a heat reflector 44 for purposes of accelerating the drying ofthe drying cloth 10 may be arranged about the heating vessel 13 whichduring operation, heats the returning portion of the drying cloth 10. Ofcourse, any suitable additional drying means for drying the cloth 10 mayalso be used. In case a single spray pipe 22 is not suflicient forheating the drum casing 6, a further spray pipe, shown in dash lines inFIGURE 4, may be provided. The heating of the section of the drum casing6 with which the drying cloth 10 is not in contact is not desirable asit is appropriate if the photographic prints to be dried which areplaced thereagainst do not encounter immediately the fully heated drumcasing 6.

Operation The operation of the heating system for the drying drum of adrying apparatus in accordance with the present invention is asfollow-s:

The water is drawn in by the pump 32 from the water sump in the lowestpart of the drum 5, 6, in proximity of the lower apex or lowest pointthereof, and is forced into the temperature control vessel or container18 where it is heated by the heating rod 34 to the adjusted temperature.The thermostat 4i assures the maintenance of an even temperature of thewater at the desired temperature. The heated water is supplied throughthe pressure line 20 to the spray pipe 22, leaves the spray pipe 22through the spray nozzles 23 in the manner indicated in FIGURE 4 andimpinges against the inside walls of the cylinder casing 6. With asuflicient speed of the water, the latter runs oif along the casing 6into the sump located within the lower region of the drum. The waterthereby gives oil. its heat to the drum casing 6.

The photographic prints to be dried are placed with the emulsion side ofthe film facing upwardly on the lower input section of the drying cloth10 and are taken along between the drying cloth 10 and the cylindercasing 6 whereby the photographic prints give off the stored dampness.The prints emerge at the upper deflecting place of the drying cloth 1dand either drop off by themselves since they have been dried in themeantime or i e taken off by a suitable deflector guide or the like.

While I have shown and described one embodiment in accordance with thepresent invention, it is understood that the same is not limited theretobut is susceptible of many changes and modifications within the spiritand scope of the present invention and I, therefore, do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifications as are encompassed by the scope ofthe appended claims.

I claim:

1. An installation for heating the drying drum of a drying apparatus forphotographic prints, comprising drum means, a relatively fixed shaft,means for rotatably sup porting said drum means about said shaft, dryingcloth means in the form of an endless band abutting against said drtunmeans over a section of the periphery thereof to press the printsagainst said drum means, said band having a portion forming an anglewith the lowermost portion of said section, said drying cloth means andsaid drum means moving in the same direction, said drum means beingconstructed in a liquid-tight manner, means for heating said drum meansin a manner such that the temperature of said drum means increases indirections upwardly firom said lowermost portion to the uppermostportion of said section, spray means disposed on the inside of said drummeans for covering a predetermined section of the drum casing with aspray of a liquid heat carrier maintained at essentially a predeterminedtemperature, said spray means being disposed below and adjacent the toppoint of said drum means and comprising a spray pipe extendingsubstantially parallel to the longitudinal axis of said drum means, saidspray pipe being provided on two sides thereof with nozzle means forangularly discharging said liquid heat carrier on pcripherally spacedportions of the inner periphery of said drum means, and securing meansfor securing said spray means on said shaft.

2. An installation for heating the drying drum of a drying apparatus forphotographic prints, comprising drum means, an essentially horizontalhollow stationary shaft, bearing means for rotatably supporting saiddrum means about said hollow shaft, drying cloth means in the form of anendless band abutting against said drum means over a section of theperiphery thereof to press the prints against said drum means, saiddrying cloth means normally moving in the same direction as said drummeans, said band having a portion forming an angle with the lowermostportion of said section, said drum means being constructed in aliquid-tight manner, means for heating said drum means in a manner suchthat the temperature of said section is lowest in the lowermost portionof said section and varies in directions upwardly from said lowermostportion to the uppermost portion of said section, a plurality of spacedspray means disposed on the inside of said drum means for spraying aplurality of sections of the drum casing with a liquid heat carriermaintained at essentially a predetermined temperature, each of saidspray means comprising a spray pipe extending substantially parallel tothe longitudinal axis of said drum means, said spray pipe being providedon two sides thereof with nozzle means for angularly discharging saidliquid heat carrier or peripherally spaced portions of the innerperiphery of said drum means, a circulatory system for each spray meansfor circulating said heat carrier including suction line means common toboth spray means and pressure line means including a separate pressureline to each spray means, temperature-controlling means tor said heatcarrier located externally of said drum means and provided withtemperature regulating means for selectively adjusting the temperatureat which said heat carrier is maintained, and circulating pump means fordrawing said heat carrier out of said drum means and for forcing thesame back into said drum means, said suction line means extending nearthe lowest point of said drum means, and said suction and pressure linemeans extending through said hollow shaft and being connected externallyof said drum means with said temperature control means and with saidpump means, said suction mid pressure line means being constructed asreadily detachable, flexible hoses adapted to be connected in a readilydetachable manner to pipe connections, and each said separate pressureline extending through an aperture in said hollow shaft toward saidspray means.

3. An installation for heating the driving drum of a drying apparatusfor photographic color prints, comprising an essentially horizontal,stationary, hollow shaft, bear-ing means rotatably supporting said drumon said shaft, an endless drying belt drivingly engaging said drum, saidbelt having a portion adapted to receive said prints and forming anangle with the lowermost portion of said drum means for heating saiddrum in such a manner that the temperature of said drum increases indirections upwardly from the said lowermost portion to the uppermostportion of said drum, said means for heating comprising spray meansdisposed within said drum for spraying the inner periphery of saiduppermost portion of said drum with a liquid heat carrier, said spraymeans comprising a spray pipe havi g nozzles closely adjacent said innerperiphery of said uppermost portion of said drum, each of said nozzlesbeing effective to direct a spray of said liquid heat carrier in adirection forming an acute angle with said inner periphery andsubstantially opposite to the direction of rotation of said drum, and aheating means and a circulating system for said liquid heat carrier'operatively connected to said spray means.

4. An installation according to claim 3, wherein said spray pipe isprovided with further nozzles directing sprays substantially in thedirection of rotation of said drum.

References Cited in the file of this patent UNITED STATES PATENTS1,763,629 Hopkins June 10, 1930 1,768,777 Muller July 1, 1930 2,373,922Tetlow Apr. 17, 1945 48,8 Saut r Apr. 10, 1 1

1. AN INSTALLATION FOR HEATING THE DRYING DRUM OF A DRYING APPARATUS FORPHOTOGRAPHIC PRINTS, COMPRISING DRUM MEANS, A RELATIVELY FIXED SHAFT,MEANS FOR ROTATABLY SUPPORTING SAID DRUM MEANS ABOUT SAID SHAFT, DRYINGCLOTH MEANS IN THE FORM OF AN ENDLESS BAND ABUTTING AGAINST SAID DRUMMEANS OVER A SECTION OF THE PERIPHERY THEREOF TO PRESS THE PRINTSAGAINST SAID DRUM MEANS, SAID BAND HAVING A PORTION FORMING AN ANGLEWITH THE LOWERMOST PORTION OF SAID SECTION, SAID DRYING CLOTH MEANS ANDSAID DRUM MEANS MOVING IN THE SAME DIRECTION, SAID DRUM MEANS BEINGCONSTRUCTED IN A LIQUID-TIGHT MANNER, MEANS FOR HEATING SAID DRUM MEANSIN A MANNER SUCH THAT THE TEMPERATURE OF SAID DRUM MEANS INCREASES INDIRECTIONS UPWARDLY FROM SAID LOWERMOST PORTION TO THE UPPERMOST PORTIONOF SAID SECTION, SPRAY MEANS DISPOSED ON THE INSIDE OF SAID DRUM MEANSFOR COVERING A PREDETERMINED SECTION OF THE DRUM CASING WITH A SPRAY OFA LIQUID HEAT CARRIER MAINTAINED AT ESSENTIALLY A PREDETERMINEDTEMPERATURE, SAID SPRAY MEANS BEING DISPOSED BELOW AND ADJACENT THE TOPPOINT OF SAID DRUM MEANS AND COMPRISING A SPRAY PIPE EXTENDINGSUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF SAID DRUM MEANS, SAIDSPRAY PIPE BEING PROVIDED ON TWO SIDES THEREOF WITH NOZZLE MEANS FORANGULARLY DISCHARGING SAID LIQUID HEAT CARRIER ON PERIPHERALLY SPACEDPORTIONS OF THE INNER PERIPHERY OF SAID DRUM MEANS, AND SECURING MEANSFOR SECURING SAID SPRAY MEANS ON SAID SHAFT.